Magnetic Resonance Imaging for Patellofemoral Chondromalacia: Is There a Role for T2 Mapping?

T2 Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation

BACKGROUND

In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T2 mapping, a well-established method for cartilage lesions assessment.

PURPOSE

To examine short-term consequences of single first-time LPD in teenagers by T2 mapping of the patellar-cartilage state.

STUDY TYPE

Prospective.

POPULATION

95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22).

FIELD STRENGTH/SEQUENCE

3.0 T; axial T2 mapping acquired using a 2D turbo spin-echo sequence.

ASSESSMENT

MRI examination was conducted 2-4 months after first LPD. T2 values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts.

STATISTICAL TESTS

ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05.

RESULTS

In lateral patellar cartilage, a significant increase in T2 values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T2 times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T2 values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T2 in the medial superficial layer (41.0 vs. 43.8 msec, 0.55).

DATA CONCLUSION

The study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY STAGE: 2.

Quantitative Magnetic Resonance Imaging Had Greater Sensitivity in Diagnosing Chondral Lesions of the Knee: A Systematic Review and Meta-Analysis

PURPOSE

To investigate the accuracy and reliability of magnetic resonance imaging (MRI) in identifying and grading chondral lesions and explore the optimal imaging technique to image cartilage.

METHOD

A comprehensive search was conducted on Medline, Embase, and Cochrane Library. Eligible cohort studies published before August 2022 were included. The study reports used MRI to diagnose and grade cartilage lesions, with intraoperative findings as the reference standard. Summary estimates of diagnostic performance were obtained. The reliability of MRI interpretation was summarized. Subgroup analyses were performed based on assessed imaging techniques, field strength, and joint surface.

RESULTS

Forty-three trials and 3,706 patients were included in the systematic review. The overall area under curve for hierarchical summarized receiver operating characteristics was 0.91 (95% confidence interval [CI] 0.88-0.93). The pooled sensitivity for quantitative MRI, 3-dimensional MRI, and 2-dimensional MRI was 0.82 (95% CI 0.64-0.92), 0.79 (95% CI 0.74-0.83), and 0.63 (95% CI 0.51-0.73), respectively. The pooled sensitivity of 3 Tesla (3T), 1.5 Tesla (1.5T), and <1.5 Tesla MRI was 0.79 (95% CI 0.72-0.85), 0.67 (95% CI 0.60-0.74), and 0.55 (95% CI 0.39-0.71), respectively. There were differences in interobserver consistency across different studies.

CONCLUSIONS

In general, MRI had high specificity in discriminating normal cartilage, but its sensitivity for identifying chondral lesions is less optimal. Further analysis showed that quantitative MRI, 3D MRI, and 3T MRI demonstrate greater sensitivity compared with 2D MRI, 1.5T MRI, and <1.5 Tesla MRI.

LEVEL OF EVIDENCE

Level III, systematic review of Level II-III studies.

Cartilage degeneration of patellofemoral joint occurs in open wedge high tibial osteotomy, rather than in hybrid closed wedge high tibial osteotomy, during the early postoperative period: A qualitative analysis using MRI T2 mapping

PURPOSE

After high tibial osteotomy, the patella may change position and osteoarthritis of the patellofemoral joint (PFJ) may occur. It was hypothesized that the course of PFJ degeneration would differ between open wedge high tibial osteotomy (OWHTO) and hybrid closed wedge high tibial osteotomy (hybrid HTO). Accordingly, this study aimed to evaluate the qualitative changes in PFJ articular cartilage, during the early postoperative period after OWHTO and hybrid HTO.

METHODS

This was a retrospective observational study of 75 knees that underwent OWHTO (N = 37) or hybrid HTO (N = 38) for medial knee osteoarthritis. OWHTO and hybrid HTO were indicated for corrections of less than 10° and more than 10°, respectively. MRI of all knees was performed before and 6 months after surgery to evaluate patellar cartilage in sagittal images for T2 mapping. Three regions of interest (medial, middle, and lateral facets) were defined in the articular cartilage, and T2 values were measured. Patellar tilting angle, lateral shift ratio, and patellar height were compared before and after surgery.

RESULTS

There was no significant change in arthroscopic findings of PFJ articular cartilage between the OWHTO and hybrid HTO groups. In the OWHTO group, the mean T₂ value of medial and middle facets increased significantly (lateral, 43.0 ± 3.9 to 43.7 ± 3.5; middle, 44.2 ± 3.9 to 46.2 ± 3.8; medial 41.0 ± 4.3 to 42.4 ± 4.0). Conversely, no significant change was observed in the hybrid HTO group (lateral, 41.1 ± 4.0 to 42.3 ± 4.0; middle, 43.6 ± 4.2 to 44.5 ± 4.3; medial, 40.7 ± 4.1 to 41.5 ± 4.5). Patellar height decreased and increased in the OWHTO and hybrid HTO groups, respectively, and patellar tilt decreased in the OWHTO group. Lateral shift ratio decreased significantly in both groups.

CONCLUSIONS

OWHTO with a small correction angle may result in qualitative changes in PFJ articular cartilage from an early stage, while hybrid HTO with a relatively large correction angle is unlikely to affect PFJ articular cartilage.

Prevalence of chondromalacia patella according to patella type and patellofemoral geometry: a retrospective study

BACKGROUND

The relationships between the morphometric structure of the patellofemoral joint, patella type and chondromalacia patella are still a matter of debate.

OBJECTIVE

To identify the prevalence of chondromalacia patella by determining the patella type and making patellofemoral morphometric measurements.

DESIGN AND SETTING

Retrospective cohort study in an orthopedics and traumatology clinic in Turkey, conducted between June 2017 and November 2019.

METHODS

This study involved 562 knees of 522 patients with anterior knee pain (246 males and 316 females; mean age 46.59 years). The patients were grouped according to presence of chondromalacia patella (group I) or absence of chondromalacia patella (group II). The patella type, lateral trochlear inclination, medial trochlear inclination, trochlear angle, sulcus angle, patellar tilt and Insall-Salvati index were assessed. Group comparisons were made using chi-square tests or Student t tests. The r value was used to determine the magnitude of relationships between pairs of variables.

RESULTS

Among the 562 knees evaluated, 265 (50.71%) presented type I patella, 195 (36.7%) type II, 100 (12.3%) type III and 2 (0.3%) type IV. Group I consisted of 448 knees and group II consisted of 114 knees. Significant differences were found between the groups in terms of age, gender, patella type and lateral inclination angles (P &lt; 0.05).

CONCLUSION

Detecting the patella type and making lateral inclination measurements in patients with anterior knee pain are of great importance for diagnosing suspected chondromalacia patella, particularly in the early degenerative period.

Magnetic resonance imaging is able to detect patellofemoral focal cartilage injuries: a systematic review with meta-analysis

PURPOSE

The purpose of this study was to analyze the diagnostic accuracy of magnetic resonance imaging (MRI) to detect and grade the severity of patellofemoral (PF) cartilage injuries.

METHODS

A systematic review was conducted on PubMed, EMBASE and Cochrane Library databases (up to July 1st 2022) to search for studies that reported the diagnostic accuracy of MRI to detect and grade PF cartilage injuries as compared to diagnostic arthroscopy. Risk of bias was judged using the QUADAS-2 tool. Quantitative syntheses were performed to calculate the diagnostic accuracy metric-sensitivity, specificity, positive likelihood (LR+) and negative likelihood (LR-) ratios, diagnostic odds ratio (DOR)-and presented as median with 25% and 75% percentiles. The summary receiver operating characteristic (SROC) curves were also calculated. Diagnostic accuracy metrics were calculated for all PF cartilage injuries and then sub-grouped by patellar and trochlear lesions. Diagnostic accuracy was also calculated according to the grading of cartilage injuries.

RESULTS

Forty-five studies were included for qualitative analyses and forty studies were included for quantitative synthesis. A total of 3534 participants with a weighted mean age of 38.1 years were included. Diagnostic accuracy was generally high: sensitivity (0.8, 0.6-1.0), specificity (0.9, 0.8-1.0), LR+ (6.4, 3.1-15.3), LR- (0.3, 0.2-0.4) and DOR (21.3, 9.9-121.1). The area under the curve (AUC) of the SROC was 0.9. The diagnostic accuracy was slightly higher for patellar (sensitivity 0.8, specificity 0.8, LR+ 5.3, LR- 0.2, DOR 28.8) than for trochlear lesions (sensitivity 0.7, specificity 0.9, LR+ 5.5, LR- 0.4, DOR 14.3). The sensitivity was generally higher when grading advanced (vs. early or intermediate) cartilage injuries of the patella.

CONCLUSION

The MRI is able to diagnose PF cartilage injuries with reasonably high diagnostic accuracy (as compared to arthroscopy). Clinicians can rely on MRI to reliably diagnose PF cartilage injuries (with some limitations) which will play an important role in deciding for surgical or non-operative treatment.

LEVEL OF EVIDENCE

Level III.

Patella-patellar tendon angle in relation to the medial patellar plica syndrome, chondromalacia patella, and infrapatellar fat pad syndrome

The patella-patellar tendon angle (PPTA) assessing the sagittal patellar tilt was reported to be related with anterior knee pain. Herein, clinical effect of PPTA in patients with medial patellar plica (MPP) syndrome, chondromalacia patella, and infrapatellar fat pad (IPFP) syndrome, the most common causes of anterior knee pain, was evaluated. In this retrospective study, 156 patients with anterior knee pain who underwent magnetic resonance imaging (MRI) and arthroscopic surgery that confirmed isolated MPP syndrome, chondromalacia patella, or IPFP syndrome from June 2011 to January 2021 were included in the study group and 118 patients without knee pathology on MRI during the same period were included in the control group. The PPTA was measured on knee MRI and compared between the two groups. A receiver operating characteristic (ROC) analysis was used to evaluate the value of PPTA for predicting the risk of patellofemoral joint disorder. The mean PPTA was significantly smaller in study group (138.1 ± 4.2°) than control group (142.1 ± 4.3°) (p < 0.001). However, there was no significant difference in PPTA among the patients with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, the ROC analysis revealed that the area under curve, sensitivity, and specificity for predicting the risk of patellofemoral joint disorders were 0.696, 70.3% and 57.6%, respectively, at a PPTA cutoff of 138.3°. Therefore, the smaller PPTA may be associated with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, PPTA could be a predictive factor for the risk of patellofemoral joint disease in patients with anterior knee pain.

Is T2 mapping reliable in evaluation of native and repair cartilage tissue of the knee?

PURPOSE

To evaluate the effect of imaging plane and experience of observers on the reliability of T2 mapping of native and repair cartilage tissue of the knee.

METHODS

Fifteen consecutive patients from two randomised controlled trials (RCTs) were included in this cross-sectional study. Patients with an isolated knee cartilage lesion were randomised to receive either debridement or microfracture (RCT 1) or debridement or autologous chondrocyte implantation (RCT 2). T2 mapping was performed in coronal and sagittal planes two years postoperatively. A musculoskeletal radiologist, a resident of radiology and two orthopaedic surgeons measured the T2 values independently. Intraclass Correlation Coefficient (ICC) with 95% Confidence Intervals was used to calculate the inter- and intraobserver agreement.

RESULTS

Mean age for the patients was 36.8 ± 11 years, 8 (53%) were men. The overall interobserver agreement varied from poor to good with ICCs in the range of 0.27- 0.76 for native cartilage and 0.00 - 0.90 for repair tissue. The lowest agreement was achieved for evaluations of repair cartilage tissue. The estimated ICCs suggested higher inter- and intraobserver agreement for radiologists. On medial femoral condyles, T2 values were higher for native cartilage on coronal images (p < 0.001) and for repair tissue on sagittal images (p < 0.001).

CONCLUSIONS

The reliability of T2 mapping of articular cartilage is influenced by the imaging plane and the experience of the observers. This influence may be more profound for repair cartilage tissue. This is important to consider when using T2 mapping to measure outcomes after cartilage repair surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02637505 and NCT02636881 , registered December 2015.

LEVEL OF EVIDENCE

II, based on prospective data from two RCTs.

Prevalence of patellar chondropathy on 3.0 T magnetic resonance imaging

Objective

To establish the prevalence of patellar chondropathy using 3T magnetic resonance imaging (MRI) and to correlate the findings with individual features such as gender, age, and body mass index.

Materials and Methods

Data consisted of collecting 3T MRIs of patients’ knees obtained between October 2016 and September 2017, comprising a period of 12 months. These MRIs were assessed by an experienced musculoskeletal radiologist who confirmed the presence of patellar chondropathy and, when present, rated the finding into the four grades ascribed by the International Cartilage Repair Society.

Results

A total number of 291 patients were assessed during the period with 389 MRI scans. Of those patients, 308 (79.2%) were diagnosed with patellar chondropathy, while 81 (20.8%) were not. Chondropathy was more prevalent in the female gender, in subjects above 40 years of age, and in obese patients. When the results were weighed in International Cartilage Repair Society classification, the milder grades (1 and 2) were seen in younger men (< 30 years of age), while the more severe grades (3 and 4) were mostly present in females, those above 40 years of age, and in obese patients.

Conclusion

There was a high prevalence of patellar chondropathy in patients who had undergone high-field knee MRIs (79.2%), being highest in the female gender and in subjects above 40 years of age. The most prevalent group was graded as 4 by the International Cartilage Repair Society classification.

Superolateral Hoffa's fat pad oedema: Relationship with cartilage T2* value and patellofemoral maltracking

PURPOSE

To determine (1) the association between superolateral Hoffa's fat pad (SHFP) oedema and early cartilage degeneration using T2* mapping and (2) whether patellofemoral maltracking is related to cartilage T2* values or SHFP oedema.

MATERIALS AND METHODS

In this retrospective study, 68 patients (71 knees) with anterior knee pain who had undergone 3-Tesla magnetic resonance imaging (MRI) were enrolled. Cartilage T2* values in medial and lateral patellofemoral compartment as well as patellofemoral maltracking parameters (trochlear angle, sulcus angle, patellar tilt angle, tibial tuberosity-to-trochlear groove [TT-TG] distance, and patellar-tendon to patellar-length [PT-PL] ratio) were compared between case group (24 knees with SHFP oedema) and control group (47 knees without the oedema). The associations between the patellofemoral maltracking and the cartilage T2* values as well as the SHFP oedema were investigated using logistic and linear regression analyses.

RESULTS

The case group showed significantly higher cartilage T2* value in the lateral patellar facet, wider sulcus angle, greater TT-TG distance, and higher PT-PL ratio than the control group. Both SHFP oedema and higher cartilage T2* value in the lateral patellar facet were significantly associated with wider sulcus angle, greater TT-TG distance, and higher PT-PL ratio.

CONCLUSION

SHFP oedema appears to be associated with inherent cartilage degeneration in the lateral patellar facet. Patellofemoral maltracking might be a risk factor for SHFP oedema and early cartilage damage in the lateral patellar facet.

The Possibilities of Magnetic Resonance Imaging in the Diagnosis of Microstructural Changes of the Subchondral Bone in Osteoarthritis

Background. Magnetic resonance imaging not only has powerful capabilities for visualization, but is also of interest in terms of obtaining ideas about microstructural and biochemical changes in the tissues of the joints in osteoarthritis.

Aims. To assess the possibility of T2-images of magnetic resonance imaging in the diagnosis of microstructural changes in the subchondral bone in osteoarthritis.

Materials and methods. 62 patients with osteoarthritis and 8 volunteers without osteoarthritis were examined. All patients underwent magnetic resonance imaging of knee. To assess the variability of transverse relaxation time, the T2-images segmentation of the subchondral segmentation in the frontal projection was performed by hand. The proton density was estimated from a 3D histogram on a scale of 0 to 255.

Results. At the first stage of osteoarthritis, the intensity of the magnetic resonance signal decreases over the entire surface of the tibial plateau, with minimal values in the region of the medial part of the knee joint. At stage 2 osteoarthritis, there was an even greater decrease in the number of protons that made the phase transition with the lowest value in the medial region. The subchondral bone texture in stage 3 was characterized by a significant decrease in signal intensity in the region of the medial plateau of the tibia. In the terminal stage of osteoarthritis.

Conclusion. The revealed regularity of the change in the relaxation time spectrum of T2-images reflects the degenerative process in subchondral bone with osteoarthritis.